The present invention relates to the field of tools for manual bending of rods, in particular for bending orthopaedic rods such as intervertebral linking elements.
The rods are typically steel or titanium rods, with a cross-section of five to six millimeters. The sought bending radii are usually comprised between twenty and one hundred millimeters. Bending requires the application of a very large force of several thousand Newtons, in particular for titanium rods.
A plurality of patents are known in the prior art that describe manual bending tools made up of two articulated arms supporting a main roller and two secondary rollers each mounted on the end of one of the two arms. Such tools are described in American patents U.S. Pat. No. 4,474,046, U.S. Pat. No. 5,490,409 and U.S. Pat. No. 5,819,580.
The patents propose the use of an adjustable main roller to optimize the bending angle of the rod.
The manual bending tools have a plurality of disadvantages.
First of all, the known implementation of bending tools involves considerable physical exercise, which is incompatible with careful, accurate manipulation: the operator must exercise a force to the limit of his or her own strength on the arms, and this obliges the operator to focus all of his or her attention on exercising this force, rather than on the precise positioning of the rod to be bent and on the permanent verification that a correct positioned is maintained. When the force is relaxed, the rod exits the head of the tool and falls. This is especially problematic in the case of orthopaedic rods that necessarily require that sterility is maintained.
A second problem relates to the limits of the bending angle. The tools of the prior art do not allow bending with very small radii of curvature, and are generally limited to radii of curvature of more than around fifty millimeters.
A third problem is that of the weight and the cleaning of said tools. In order to withstand the considerable forces applied by the user, these tools generally have solid metal arms, and articulations that have areas where dirt may accumulate.